In my more recent prior application there is disclosed a percussor assembly utilizing a diaphragm sealing means between a gas pressure chamber communicating with a gas outlet passageway, whereby gas pressure from a pressurized gas source builds up in the chamber until it overcomes a gas seal created by the biased diaphragm against a valve seat. When the gas seal is broken, a burst or pressure wave of gas passes from the gas pressure chamber through the outlet passageway to a remote percussor head or applicator pneumatically connected to the gas outlet passageway. A disadvantage of the prior percussor assembly is that all of the gas directed to the applicator originates from the gas pressure source so that over prolonged periods of use, the volume of gas required to operate the unit may be significant. Where the pressurized gas source is oxygen operating costs may be substantial.